Conventionally known general resist materials are polymer materials capable of forming amorphous thin film. For example, a solution of a polymer resist material such as polymethyl methacrylate, polyhydroxystyrene having an acid-dissociable reactive group, polyalkyl methacrylate or the like is applied onto a substrate to form a thin resist film, which is then irradiated with ultraviolet rays, far ultraviolet rays, electron beams, extreme ultraviolet rays (EUV), X-rays or the like to form line patterns having a width of about 45 to 100 nm.
However, the polymer resist compounds have a molecular weight as large as about 10,000 to 100,000 and a broad molecular weight distribution. Therefore, in the lithography using the polymer resist compound, roughness is caused on the surface of the fine pattern and it is difficult to control dimension of the pattern and hence the yield ratio lowers. In the lithography using the conventional polymer resist material, therefore, there is a limit in fine processing. To this end, various low molecular weight resist materials have been proposed for preparing finer patterns.
For example, there have been proposed an alkali-developable, negative-type radiation sensitive compositions using a low molecular weight, polynuclear polyphenol compound as a main component (see JP-A-2005-326838 and JP-A-2008-145539). However, there are drawbacks that these compositions are insufficient in the heat resistance and the shape of the resulting resist pattern becomes poor.
As the low molecular weight resist material are proposed alkali-developable, negative-type radiation-sensitive compositions using a low molecular weight, cyclic polyphenol compound as a main component (JP A-2009-173623 and T. Nakayama, M. Nomura, K. Haga, M. Ueda: Bull. Chem. Soc. Jpn., 71, 2979 (1998)).
These low molecular weight cyclic polyphenol compounds are expected to provide resist patterns being small in the molecular size, high in the resolution and small in the roughness because of their low molecular weights. In addition, the low molecular weight, cyclic polyphenol compound imparts a high heat resistance though it has a low molecular weight because of a rigid cyclic structure in its skeleton.
However, the conventionally known low molecular weight cyclic polyphenol compounds have several drawbacks that the solubility in safety solvents used in semiconductor production process is low, and the sensitivity is low, and the shape of the resulting resist pattern is bad. Therefore, it is desired to improve the low molecular weight cyclic polyphenol compounds.